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The anhydrous proton conductivity of Im@IEF-11 resulting from the integration of imidazole and porous IEF-11 has been investigated, and the highest proton conductive value can reach up to 7.64 × 10−2 S cm−1. Furthermore, IEF-11 is also developed to reduce CO2 due to its reasonable structure and suitable energy band, and its CO formation rate is 31.86 μmol g−1 h−1. [ABSTRACT FROM AUTHOR]

The photocatalytic conversion of CO2 into widely adjustable syngas (CO/H2 mixture) has been considered as an extraordinarily promising but challenging strategy to realize high value-added utilization of CO2 to alleviate worldwide environmental problems and energy crisis. To achieve this goal, we report a newly designed crystalline covalent organic framework (COF-TVBT-Bpy) that embedded a series of metal active sites to efficiently convert CO2 and H2O into syngas under visible-light illumination. COF-TVBT-Bpy not only provides a coordination environment for the metal center, but also enhances electron delocalization by the extended conjugated moiety, thus facilitating electron transfer. The optimized Co@COF-TVBT-Bpy achieves the highest photocatalytic CO2-to-syngas conversion efficiency in pure CO2 (up to 2291.1 μmol g−1 h−1, CO/H2 ≈ 1 : 1). The intrinsic reason for a CO/H2 ratio of 1 : 1, electron transfer pathway, and syngas generation mechanism over Co@COF-TVBT-Bpy are explored by the combination of in situ measurements and theoretical calculations. The experimental results confirm that the ratio of CO/H2 can be widely modulated by adjusting the metal active sites and photoreaction conditions. This work proves the immense potential of utilizing COFs as platforms to anchor metal active sites for syngas formation and provides a facile method to regulate the ratio of syngas in a wide range. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) provide an ideal platform for loading various guests owing to their available space, and can be developed as a class of multifunctional materials. Herein, we cover the design and synthesis of two kinds of exchanged frameworks with multifunctional applications based on H3ImDC and In(NO3)3·2H2O through guest exchange inside the framework. The guest ammonium ion (NH4+) and [Ru(2,2′-bipyridine)3]2+ (Rubpy) are selected to exchange the dimethylammonium cation (Me2NH2+) encapsulated within In-MOF, giving birth to two kinds of new MOFs, named NH4+@In-MOF and Rubpy@In-MOF respectively. The proton conduction of NH4+@In-MOF and the CO2 photoreduction of Rubpy@In-MOF are investigated. Under different test conditions, the proton conductive behaviors of NH4+@In-MOF are evaluated and the best proton conductive value can reach up to 9.81 × 10−3 S cm−1. Compared to the original In-MOF, Rubpy@In-MOF exhibits a significantly enhanced CO2 photoreduction performance under a pure CO2 atmosphere. Furthermore, its photocatalytic activity is retained even under a 10% CO2 gas atmosphere, displaying a synergistic effect between Rubpy and In-MOF24 within Rubpy@In-MOF. [ABSTRACT FROM AUTHOR]

The conversion of CO 2 into useful chemicals via photocatalysts is a promising strategy for resolving the environmental problems caused by the addition of CO 2 . Herein, a series of composite photocatalysts MOP@TpPa-CH 3 based on MOP-NH 2 and TpPa-CH 3 through covalent bridging have been prepared via a facile room-temperature evaporation method and employed for photocatalytic CO 2 reduction. The photocatalytic performances of MOP@TpPa-CH 3 are greater than those of TpPa-CH 3 and MOP-NH 2 , where the CO generation rate of MOP@TpPa-CH 3 under 10% CO 2 still reaches 119.25 μmol g -1 h -1 , which is 2.18 times higher than that under pure CO 2 (54.74 μmol g -1 h -1 ). To investigate the structural factors affecting the photocatalytic activity, MOP@TBPa-CH 3 without C═O groups is synthesized, and the photoreduction performance is also evaluated. The controlling experimental results demonstrate that the excellent photoreduction CO 2 performance of MOP@TpPa-CH 3 in a 10% CO 2 atmosphere is due to the presence of C═O groups in TpPa-CH 3 . This work offers a new design and construction strategy for novel MOP@COF composites.

The anhydrous proton conductivity of Im@IEF-11 resulting from the integration of imidazole and porous IEF-11 has been investigated, and the highest proton conductive value can reach up to 7.64 × 10 -2 S cm -1 . Furthermore, IEF-11 is also developed to reduce CO 2 due to its reasonable structure and suitable energy band, and its CO formation rate is 31.86 μmol g -1 h -1 .

The photoreduction deposition method is employed to fabricate a family of silver nanoparticle (Ag NP)-modified polyoxometalate-based metal-organic framework ( NENU-5 ) photocatalysts, named Ag/NENU-5 . The title photocatalysts, Ag/NENU-5 , can be used for the photocatalytic reduction of CO 2 and are observed to efficiently reduce CO 2 into CO, in which the highest reduction rate is 22.28 μmol g -1 h -1 , 3 times greater than that of NENU-5 . Photocatalytic reduction performances of CO 2 have been extremely improved after the incorporation of Ag NPs as the cocatalyst. The enhancement of the photocatalytic reduction of CO 2 has been attributed to the synergistic effects of Ag NPs and NENU-5 , inhibiting the charge recombination during the photocatalytic process and increasing the reaction active sites. Furthermore, the influence of Ag NPs on the photocatalytic activity has also been investigated. The experimental results clearly reveal that the size of Ag NPs could exert a main effect on the photocatalytic activity, and the reasonable size of Ag NPs is able to enhance the photocatalytic reduction activity toward CO 2 significantly.

Metal-organic frameworks (MOFs) provide an ideal platform for loading various guests owing to their available space, and can be developed as a class of multifunctional materials. Herein, we cover the design and synthesis of two kinds of exchanged frameworks with multifunctional applications based on H 3 ImDC and In(NO 3 ) 3 ·2H 2 O through guest exchange inside the framework. The guest ammonium ion (NH 4 + ) and [Ru(2,2'-bipyridine) 3 ] 2+ (Rubpy) are selected to exchange the dimethylammonium cation (Me 2 NH 2 + ) encapsulated within In-MOF , giving birth to two kinds of new MOFs, named NH 4 + @In-MOF and Rubpy@In-MOF respectively. The proton conduction of NH 4 + @In-MOF and the CO 2 photoreduction of Rubpy@In-MOF are investigated. Under different test conditions, the proton conductive behaviors of NH 4 + @In-MOF are evaluated and the best proton conductive value can reach up to 9.81 × 10 -3 S cm -1 . Compared to the original In-MOF , Rubpy@In-MOF exhibits a significantly enhanced CO 2 photoreduction performance under a pure CO 2 atmosphere. Furthermore, its photocatalytic activity is retained even under a 10% CO 2 gas atmosphere, displaying a synergistic effect between Rubpy and In-MOF24 within Rubpy@In-MOF .

It is a promising strategy to prepare composite photocatalysts based on MOFs and semiconductors for enhancing photocatalytic reduction of carbon dioxide (CO 2 ). A family of binary composite photocatalysts ( CdS@UiO-66-NH 2 ) with different CdS contents have been designed and synthesized, which have been explored for photocatalytic reduction of CO 2 . CdS@UiO-66-NH 2 can efficiently convert CO 2 into CO under visible light irradiation via the solid-gas mode in the absence of sacrificial agents and photosensitizers. The generation rate of CO can reach up to 280.5 μmol g -1 h -1 , which is 2.13-fold and 2.9-fold improvements over the pristine CdS and UiO-66-NH 2 , respectively, and the selectivity for CO is very high. Furthermore, this kind of photocatalysts can still maintain great photocatalytic activity in CO 2 /N 2 mixed atmosphere with different CO 2 concentrations. The outstanding performances of CdS@UiO-66-NH 2 may be attributed to the existence of the direct Z-scheme heterojunction, which possesses the enhanced separation and migration of photo-generated charge carriers between UiO-66-NH 2 and CdS, available specific surface areas and improved visible light absorption ability as well as abundant reaction active sites. This case reveals that MOF-based composite photocatalysts exhibit promising potential applications in the field of CO 2 conversion.